A system for the switching and transmission of packetized information is disclosed in the above-identified applications. For example, J. S. Turner, U.S. Pat. No. 4,490,230 describes a system comprising fast packet switching networks interconnected by high-speed digital trunks with each trunk being terminated on both ends by a trunk controller.
A communication path is set up through that system by initially routing a call setup packet from an originating terminal to each central processor controlling a switching network in the route to the destination terminal. Each central processor is responsive to a receipt of the setup packet to store logical to physical address translation information in memories of its associated trunk controllers. The physical address defines a path through the switching network to an output trunk controller in the communication path to the destination terminal. In response to receipt of each subsequent message packet, each trunk controller utilizes its memory information for translation and the assemblage of a new packet containing the physical address plus the message packet. The controller then sends the new packet to the switching network. The switching network comprises switch nodes which are responsive to the physical address in the new packet for establishing the physical path to the output trunk controller.
A problem in such packet switching networks is that, if a switch node fails to route a received packet or erroneously creates a packet, this can only be detected at the edges of the packet switching system. Whereas, modern packet protocols such as X.25 (CCITT, 1976, Amended 1980) detect such errors at the edges of the packet switching system; such detection takes a great deal of time during which the reliability and accurate switching of many packets is adversely affected.